Once upon a time I got into a ranked game late at night with a Darius and Blitz that were duo queue trolls. I typically try to just be nice and let the game play out, and sometimes things will turn around and we'll win anyway. Nope. It was awful. The Darius came mid with me the entire game and fed, not to mention stole all the farm, and his friend who went Blitz followed our jungler around and trolled him in the same way, stealing the camps. They both fed really hard and we lost pretty early (naturally they refused to surrender) to no surprise. The odd part was, not a single person on the team was flaming them the entire time. We just kind of let them derp.
Blocked / Reported, whatever - load into the next game.
With the same 2 players...they did the SAME thing, and those 2 trolls singlehandedly lost me my promos into Silver. The worst possible league experience I have ever had - and matchmaking trolled me really hard.